Thermocouples mounting

The temperature control of the furnace is satisfactorily achieved via a thermocouple mounted very close to the furnace-winding. The maximum operational temperature may be obtained by using different thermocouples as indicated below ... 

The black panel temperature is measured with a thermocouple mounted on a flat black painted panel which is placed on the sample rack of the Weather-Ometer. As such, the temperature registered is meant to indicate a maximum temperature of the specimens under the same irradiation. 

Fio. 2. Photo of tip of a sample holder for heating the catalyst specimen during exposure to reactive gases. The holder body suspends a cup with the TEM specimen grid. The cup is thermally and electrically isolated from the holder body and can be heated by a tungsten filament located inside the cup. The temperature is measured by a thermocouple mounted on the outside of the cup. 

The dynamics of heating in the initiation region was studied with the help of a copper-constantan thermocouple mounted on the heater surface (not shown in Fig. 2). The results of the measurements are presented in Fig. 3 (the arrow indicates the instant of switching on the pulse heater). Whatever the pulse energy, no reaction burst is observed in nonirradiated samples after switching on the heater (Fig. 3, solid curve). In the preirradiated CB + Cl2 system,... 

Each reactor was heated in an enclosing furnace controlled by an Omega temperature controller. All temperatures were monitored by l/16in Inconel-sheathed thermocouples mounted on the feed side Details regarding sampling and analysis are reported in [2]. The entire reactor/analytial system was configured to operate for long periods of time (lyr) under fixed-conversion variable-temperature conditions. 

The VOC oxidation reaction was studied using a fixed tod and two fluid bed iaboratoi scale quaitz teactors, operated continuously at atmosphcfic pressure. Each reactor was heated in a tube furnace to the reaction temperature wTuch was controlled to 1 C by an Omega CN-9000 temperature controller. The reactor inlet temperature was measured by a 1/ld inch [nconcl sheathed thermocouple mounted inside Ihc reactor on the feed side. 

The calibration of the temperature of the furnace and/or sample chamber has been discussed by Stewart (12) and Norem et al. (14, 15). Stewart (12) used a conventional thermobalance which contained a thermocouple mounted external to the sample, while Norem et al. (14, 15) calibrated a furnace which used a resistance element for lemperature detection. 

This technique is very simple and of low cost. However, only the average heat flux over the entire solid is determined. It also relies on an accurate value of the target emissivity. It has only limited practical relevance and it is limited by the permissible maximum material temperature level of the solid. Also, the solid should be uniformly heated to obtain an accurate average measurement. Nonuniform heating complicates the energy balance calculations. In Kilham s studies [17,18], the cylinders were rotated to minimize surface temperature gradients. However, only a single thermocouple, mounted on the inside diameter of the hollow cylinder to measure the inside cylinder temperature, was used to calculate the surface temperature. 

An additional external heating source was used to solve this problem. Two Osram Xenophot HLX 64 635 (15 Volt, 150 Watt) IR heaters mounted on moveable support arms were used to heat the MS capillary tip, a third one was used to heat the FTIR capillary tip. These three heaters are controlled by one Eurotherm 808 controller with the measuring and the alarm thermocouples mounted near the small ball-joint of the MS heated transfer line/TGA furnace coupling, see Figure 6.6. The measurement of the FTIR/MS capillary tip temperatures was repeated using only these extra heating sources (no TGA furnace switched on), the results are listed in Table 6.2. 

The black panel temperature is measured with a thermocouple mounted on a flat black painted panel which is placed on the sample rack of tire Weatlier-Ometer. As such, the temperature registered is meant to indicate a maximum temperature of the specimens under tire same iiTadiation. Kockett, D., Factors of weathering. Presentation given at tire Atlas School of Natural and Accelerated Weathering (ASNAW) course, Miami, FL, 27-30 April, 1999, Atlas Electric Devices company, Chicago, IL, 1999. 

The silver chloride 5X treatment unit was an electrically heated oven with forced-air circulation to prevent cold spots. The temperature of the silver chloride was measured with a thermocouple mounted in the unit. The vent air from the unit containing nitric acid vapors was passed through a condenser prior to flowing into the main plant off-gas system. 

The sample is positioned in a temperature-control chamber which contains a radiant heater and a coolant distribution system. The radiant heater provides precise and accurate control of sample temperature. The coolant distribution system uses cold nitrogen gas for smooth, controlled sub-ambient operation and for quench cooling at the start or end of a run. Both the radiant heater and the coolant accessory are controlled automatically by the 983 system to ensure reproducible temperature programming. An adjustable thermocouple, mounted close to the sample, provides precise feedback information to the temperature controller, as well as a readout of sample temperature. 

Nernst, Koref, and Lindematm (1910) described an aneroid drop calorimeter for the measurement of specific heat capacities. Figure 7.14 shows the design of this instrument. The entire system is located in isothermal surroundings such as melting ice. Of particular interest is the measurement of the temperature change of the calorimeter substance by means of 10 iron-constantan thermocouples mounted between the calorimeter substance and the isothermal Ud. 

Bearing temperature was monitored with a thermocouple mounted in the wall of the bush, approximately 2mm from the bearing surface and In line with the applied load. 

Changes in liquid level and ullage-space temperature gradient during tests were read out on a strip-chart recorder. The signals for this recorder were generated by seven thermocouples mounted at equal intervals of height on a "tree" mounted within the tank. 

Thermocouple mounted 0.5 inches behind orifice exit. 

In the tangential machine a thermocouple mounted in the end frame is more robust, but is often far less responsive than one mounted in the door top, although recent rotor designs which improve material flow to the ends of the mixing chamber should have improved the response of endframe thermocouples. Infrared probes are most commonly fitted in an endframe. 

Figure 11. Scheme of one of the microcalorimeters used for the simultaneous measurements of O2 consumption and heat production rates in perfused preparations. The thermal gradient layers (1) are made of semiconductor thermocouples mounted in series on each chamber. The preparation (2) is placed near the upstream extremity of one of the 8-cm long tantalum chambers, so that most of the heat it produces is transmitted to the surrounding aluminium block that functions as a heat sink. The four-way distributor, driven from outside the thermostatic jacket by a torsion bar and a pneumatic valve, directs the effluents of the preparation chamber and the control chamber to the drain, alternately via a jet in front of the O2 cathode (3) or directly (4) every 2 to 5 min. Immediately upstream of the calorimeter chambers, the downstream components of the heat exchangers (5) are wound together, in co-current, in close contact with an extension of the aluminium block (not represented on the drawing) (Reproduced from Reference [70] with permission). 

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